1. Field of the Invention
The present invention relates to a slurry for planarizing metals by chemicalmechanical polishing (CMP) with improved planarity. The present invention is applicable to manufacturing high speed integrated circuits having submicron design features and high conductivity interconnect structures with high production throughput.
2. Background of the Related Art
In the fabrication of integrated circuits and other electronic devices, multiple layers of conducting, semiconducting, and dielectric materials are deposited on or removed from a surface of a substrate. Thin layers of conducting, semiconducting, and dielectric materials may be deposited by a number of deposition techniques. Common deposition techniques in modem processing include physical vapor deposition (PVD), also known as sputtering, chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), and now electrochemical plating (ECP).
As layers of materials are sequentially deposited and removed, the uppermost surface of the substrate may become non-planar across its surface and require planarization. Planarizing a surface, or xe2x80x9cpolishingxe2x80x9d a surface, is a process where material is removed from the surface of the substrate to form a generally even, planar surface. Planarization is useful in removing undesired surface topography and surface defects, such as rough surfaces, agglomerated materials, crystal lattice damage, scratches, and contaminated layers or materials. Planarization is also useful in forming features on a substrate by removing excess deposited material used to fill the features and to provide an even surface for subsequent levels of metallization and processing.
Chemical mechanical planarization, or chemical mechanical polishing (CMP), is a common technique used to planarize substrates. CMP utilizes a chemical composition, typically a slurry or other fluid medium, for selective removal of material from substrates. In conventional CMP techniques, a substrate carrier or polishing head is mounted on a carrier assembly and positioned in contact with a polishing pad in a CMP apparatus. The carrier assembly provides a controllable pressure to the substrate urging the substrate against the polishing pad. The pad is moved relative to the substrate by an external driving force. Thus, the CMP apparatus effects polishing or rubbing movement between the surface of the substrate and the polishing pad while dispersing a polishing composition, or slurry, to effect both chemical activity and mechanical activity.
Conventional CMP processes are performed using an abrasive article, such as a polishing composition, or slurry, containing abrasive particles in a reactive solution with a conventional polishing pad. Alternatively, the abrasive article can be a fixed abrasive article, such as a fixed abrasive polishing pad, which may be used with a CMP composition or slurry that does not contain abrasive particles. A fixed abrasive article typically comprises a backing sheet with a plurality of geometric abrasive composite elements adhered thereto.
The chemical compositions used in CMP typically include multiple components such as oxidizing agents and complexing agents. The compositions may further include abrasive particles, such as colloidal silica, as the abrasive component. The components are typically combined prior to the delivery of the composition to the pad for polishing. The various components may interact with one another or otherwise degrade resulting in a less effective formulation. A typical pot life, e.g., the effective period of the slurry, may be twenty four (24) hours or less under certain polishing performance requirements.
Therefore, there exists a need for a method and CMP composition that has an extended pot life and maintains an effective polishing result.
Aspects of the invention generally provide a method and composition for planarizing a substrate surface including planarizing metals, such as Cu and Cu alloys, with reduced dishing, improved surface planarity, increased throughput, and reduced manufacturing costs.
In one aspect, the invention provides a slurry for chemical mechanical polishing a metal comprising a reagent having a first moiety for oxidizing the metal and for complexing with the metal and/or oxidized metal and a second moiety for minimizing overetching the metal. The slurry may further include abrasive particles, inhibitors, pH adjusting agents, and combinations thereof.
In another aspect, the invention provides a method for planarizing a surface of a metal layer by chemical mechanical polishing the surface with a slurry comprising a reagent having a first moiety for oxidizing the metal and for complexing with the metal and/or oxidized metal and a second moiety for minimizing overetching of the metal. The slurry may further include abrasive particles, inhibitors, pH adjusting agents, and combinations thereof.